1. Field of the Invention
This invention relates generally to a method of forming a protrusion extending from a thermoplastic part and, more particularly, to a method of forming a locating and/or fastening stud integral with and extending from a back surface of a thermoplastic body trim strip or molding strip associated with a vehicle in which the locating protrusion is formed from the thermoplastic material of the strip.
2. Discussion of the Related Art
Vehicle body trim strips or molding strips that are flexible and have a thermoplastic base layer that includes a substantially planar back surface to be positioned against and fastened to a vehicle body part are well known in the art. Generally, these molding strips include a series of protruding members extending from the back surface of the strip which are inserted into associated openings extending through the vehicle body part so as to align the molding strip with the vehicle, and, in some cases, provide a mechanism for attaching the molding strip to the vehicle. For many years, various protruding members have been welded to the thermoplastic portions of these molding strips to perform locating and fastening functions. In some of these implementations, the protruding members are molded into the thermoplastic portions by an applicable die apparatus when the molding strip is formed.
U.S. Pat. No. 4,631,104 issued to Jackson, and assigned to the assignee of the instant application, discloses a thermoplastic vehicle trim strip or molding strip having a metal stud or mounting member secured to the strip in order to provide a mechanism for locating the strip relative to the vehicle. The mounting stud includes a base portion that is embedded in the thermoplastic material of the strip. Before the mounting stud is secured to the strip, the base portion is heated to a temperature sufficient to cause the base portion to melt the thermoplastic material of the trim strip. When appropriate pressure is applied to the mounting stud, the base portion of the stud will melt the thermoplastic material so as to become embedded in the trim strip and retained there once the thermoplastic material cools. Elongated adhesive strips positioned adjacent the mounting studs serve to secure the molding strip to the vehicle.
Although the above-described mounting stud for a vehicle trim or molding strip has been relatively effective, there still remains room for improvement of this procedure. Particularly, because the mounting stud is made of a metal, corrosion and oxidation of the stud may present a problem over time in that the mounting stud may break resulting in the molding hanging off and/or falling from the vehicle. Further, the cost of the fasteners and the tools required to manufacture these mounting studs are excessive in today's cost competitive environment. Additionally, use of a rigid metal part used in connection with the molding strip provides a level of risk of damaging the aesthetic face and related thermoplastic materials of the trim strip during packaging and transportation of the trim strips as a result of the metal part contacting adjacent trim strips. Also, the process of fastening metal studs to moldings is time consuming and difficult.
What is needed is a locating protrusion on a vehicle trim strip which at least attempts to alleviate the drawbacks mentioned above. It is therefore an object of the present invention to provide such a trim strip.